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O. P. BUSHNELL.

COMBINATION EXTENSION LADDER.

UNITED STATES PATENT OFFICE.

COMBINATION EXTENSION-LADDER.

SPECIFICATION forming part of Letters Patent No. 480,655, dated August9, 1892. Application led December 1, 1891. Serial No. 413,634. (Nomodel.)

To all whom t may concern,.-

Beit known that I, CYRUS l. BUsHNELL, of the city of Providence, in thecounty of Providence and State of Rhode Island, have invented certainnew and useful Improvements in Combination Extension-Ladders; andI.hereby declare that the following is a full, clear, and exactdescription of the same, referencebeinghad totheaccompanyingdrawings,forming part of this specification.

This invention has reference to improvements in combinationextension-ladders.

The object of the invention is to produce an extension-ladder whichshall be durablein construction and effective in operation.

The invention consists in the peculiar construction of the ladders andthe combination therewith of the novel devices by which the ladders aresupported and operated, as will be more fullydescribed hereinafter, andpointed out in the claims.

Figure l represents a front elevation of my improved extension-'ladderand the side pole pivotally secured thereto. Fig. 2 represents avertical sectional view of the two parts of the ladder and indicates theoperation of the same. Fig. 3 represents an enlarged View, partly invertical section, of portions of the two ladders, showing the lockingdevice secured to one ladder andinterlocking with the rounds of theother ladder. Fig. 4 represents a similar view of the same portions, thelocking device being shown in the unlocked position. Fig. 5 representsan enlarged crosssectional view of portions of the ladderframes, showingthe roller-bearing and the sliding clamp, by which the base ends of theladders are secured together. Fig. 6 represents a similar view of theupper portion ot' the ladders, With the roller-bearing and sliding clampcarried by the base ladder. Fig;

7 represents an enlarged View of portions of the ladder-frames and thelatch plate by which the pivoted shank of the side pole is secured tothe base-ladder. Fig. 8 represents a cross-sectional view of the samewith the shank of the side pole locked in place.

Similarnumbers of reference designate corresponding parts throughout.

In the drawings, 10 indicates a base-ladder of ordinary construction. Tothe inner surface of the side frames of this ladder, near the upperends, are secured the plates ll, having longitudinal slots cut throughthe same and having the turned-over edges 12 12, inclosing thelatch-plate 13, which has the longitudinal slot 14, enlarged at thelower end. This latch-plate has also a thumb-piece 15, by which theplate is moved. In the side frames of the base-ladder directly oppositethe slots in the plate ll is secured in a suitable recess the metalsocket 16, having the outer enlargements 17, only one of which is shown.

The side poles 18 have at their upper ends the metal end pieces 19,between the arms of which the shank or stud20 is pivoted. This stud hasan enlarged circumferential shoulder adapted to iit the enlarged portionof the socket 1G, the end of the vstud extending through said socket andhaving a contracted neck 22, With which the narrow upper portion of theslot l-t when the latch-plate 13 is pushed downward securely pivots thestud 20 to the base-ladder l0. The weight of the ladder will now besupported by the large circumferential shoulder 2l ofthe stud 20, whichAis more durable than the small shank of the stud.

Near the upper end of the ladder l0, at points above the side-polelatches, the rollerbearings 23 are journaled on suitable shafts securedto the inner surfaces of theladderframe, and at these points on theladder 10 are also secured the clamping-irons 24 24, the bent ends ofwhich are adapted to hold the extension -ladder 25 from falling outward,while saideXtension-ladder is free to'slide on the roller-bearin gs andis guided by the clamping-irons.

The extension-ladder 25 is of a Width to fit between the side frames ofthe base ladder 10, and is provided near itshlower end with the casings26, having the clamping-arms 27 adapted to move over the outer and lowervSide-frame surfaces of the ladder 10. This casing 26 is also furnishedwith the roller 28, bearing on the upper edges of the side frames of theladder 10 and journaled on shafts secured in said casings.

The locking devices by which the extension-ladder 25 is secured at anypoint in the length of the base-ladder l0 are contained within thecasings 29, mortised into the under IOO edges of the extension-laddernear the lower end thereof, these casings 29 protecting the lockingmechanism from contact with the wooden portions of thc ladder, so thatthese movable parts are not affected by the expanxo casing is secured inplace.

I5 cured in the side walls of the casing. These locking-arms 34 havejaws formed between the lips 35 and Bti-that marked36 extending beyondthat marked 35-a-nd at the rear npper portion of this arm is formedthestop 37,

which strikes against the stop 33 of the cashas, also,a cam-shoulder 42,working over the i ing when the lower end of this arm is pressed outwardby the spring 38, which is bent over the post 39, its end being securedunder the upper end ofthe casing.

The key 40 is journaled on the shaft 41, the ends of which are securedin the sides of the casing in a position so that when forced i-nward itwill engage the lip 36 and push the lockingarm into the casing 29. Thiskey `40 spring 43, which is bent over the post 44, the end being securedunder the lower endof the casing 29.

To the top round of the ladder 10 is se- 3 5 cured the pulley 45,through which the rope 46 is passed, one end being secured to one of thelower rounds of the extension-ladder 25. The other end of this rope isfree, and if suficient pull is exerted on this free end the ex- 40 tension-ladder willbe raise dland wil ve ry readily travel over theroller-bearings 23 and 28. When this extension-ladder has been raised tothe proper height, it is allowed to slip backward a short distance, thelocking-arm 34 will 4 be pressed outward bythe spring 38, Yand the jawbetween the lips 35 and 36 will inter-ii lock with one of the rounds ofthe ladder 1-0. When it is desired to lower the extensionladder it isfirst elevated to bring the rounded 5o outer edge of the lip 35 to bearagainst the` under side of one of the rounds of the baseladder, as isshown in Fig. 4. The extension is then suddenly dropped, and when thekey 40 is struck by .the next round it also is brought into the positionshown in Fig. 4,

these parts remaining in said positions durv ing the rapid downwardmovement of the ext tension-ladder. Ii', however, this ladder 25:carrying the locking device is stopped in its 1 6o downward course in aposition to bring the;

locking devices between the rounds of the l ladder 10, the springs willoperate to force the locking-arm and the key outward. It' the exitension-ladder is now raised to bring a round of the ladder 10 betweenthe jaw of the locking-arm and the key 40, the rope may be released andthe ladders will automatically lock together.

Having thus described my invention, I claim as new and desire to secureby Letters Patent- 1. The combination, with a ladder provided with metalsockets extending through the side frames and having an outer enlargedportion, of studs or shanks pivotally secured to side poles adapted toextend through said sockets and furnished with enlargements adapted torotate in the enlarged portions thereof, and means for pivotallysecuring said studs in the sockets, as described.

2. The combination, with the ladder 10, provided with the perforated yorslotted plates 11 and the latch-plates 13, having the slots 14 movabletherein, the sockets 1G, extending through the side frames of saidladder opposite said plates 11, and having the enlarged portions 17 ofthe studs `20 pivotally secured to the side poles, and having theenlarged shoulders 21, `adapted to rotate in the enlargements 17 of saidsockets, and the contracted necks 22, to be engaged by the slots 14 ofthe latch-plates to pivotally secure said studs in place, `as and forthe purpose described.

3. The combination, with the ladder 10, provided at the upper portionwith the rollerbearings 23 journaled on a shaft secured to the sidetrames, and the clamping-irons 24, also secured thereto, of the ladder25, provided with the casings 26, having the clamping-arms 27 and theroller-bearings 28, journaled on shafts secured in said casings, andmeans for automatically locking said ladders together, as described.

4. An automatic locking device for extension-ladders, consisting of aspring operated locking-arm journaled in a casing adapted to be securedto one section of the ladder, and having a jaw formed between twodownward 'ly-extending lips, and a spring-operated key also journaled insaid casing and adapted to enter the jaw of the locking-.arm to depress:said arm, as described.

5. In a locking device for extension-ladders, the combination, with th-ecasing 29, having the stop 33 formed on one end thereof, ot' thevlockimg-.arm 34, jonrnaled on a shaft secured in said casing and havingthe stop 37, and lips 35 and 36, and operated by the spring 38, securedas described, and the key 40, journaled on the shaft 41, secured insai-d casing, and having the cam-shoulder 42, and a spring 43 bearingagainst said shoulder, as and for the purpose described.V

CYRUS P. BUSHNELL.

Witnesses:

J. A. MILLER, Jr., HENRY J. MILLER.

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